The present invention relates to an apparatus for handling substrates having an inner hole, and includes an inner gripper and an outer gripper; the present invention also relates to a method of handling substrates that have an inner hole, according to which a first substrate is grasped by an inner hole gripper.
Methods and apparatus of this type are described, for example, in the not prepublished DE-A 197 18 471, which belongs to the assignee of the present application, and that to avoid repetition is incorporated by reference to the extent relevant to the subject matter of the present invention. With the apparatus described for adhesively joining two substrates, a plurality of apparatus are described for handling substrates, and will subsequently be designated as handlers. One of these handlers, which serves for the transport of substrates from a circular switching table to an adhesion station, is provided with an inner gripper and an outer gripper that are each embodied as a so-called vacuum gripper. This particular handler operates by first removing a first substrate from the circular switching table with the inner gripper, bringing the substrate to an adhesion station, and depositing it there. Subsequently, the handler is moved back to the circular switching table. There it takes up a second substrate with the inner gripper and brings it into contact with the outer gripper, whereby the cooperation of the inner gripper with the outer gripper produces a distortion in the second substrate. The second substrate is subsequently moved to the adhesion station, where it is placed upon the first substrate, upon which an adhesive has been applied.
With the described handler, only one substrate can be taken up and transported at any given time. Furthermore, in order to accelerate the release of the vacuum gripper, during release of the gripper not only must the vacuum be eliminated but in addition a positive air blast is applied to the substrate. In so doing, however, there exists the danger that in particular during release of the inner gripper, air will be blown in between the two substrates that are to be adhesively joined; this is undesirable since it can lead to air bubbles in the adhesive located between the substrates.
In the apparatus described in DE-A-197 18 471, inner hole grippers are also used at other locations and respectively engage an inner hole of a substrate or the substrates that are adhesively joined to one another in order to then be able to transport the substrates. However, the inner hole grippers can only receive and transport a single substrate, or a unit of order to then be able to transport the substrates. However, the inner hole grippers can only receive and transport a single substrate, or a unit of adhesively joined substrates.
DE-A-1 95 29 537 discloses an apparatus for grasping and holding a flat substrate having an inner hole, according to which a plurality of finger-like grippers that are pivotably mounted in a housing are introduced into the inner hole of the substrate and are subsequently pivoted outwardly in order to hold the substrate at the inner hole. In the publication xe2x80x9co+p-xc3x6lhydraulik und pneumatikxe2x80x9dxe2x88x9222 (1978) Nr 1, page 10, various grippers that are pneumatically actuateable are illustrated. In this connection, among others an inner hole gripper is described. With the inner hole grippers known from DE-A-1 95 29 537 and from the publication there results the problem that in each case only a single substrate can be handled.
It is an object of the present invention to provide an apparatus and a method for handling substrates that enable the simultaneous handling of a plurality of substrates, yet are structurally straightforward and capable of being easily carried out, and also enable a high productivity. A further object of the present invention is to provide an apparatus and a method for handling substrates that have an inner hole, according to which an aforementioned type, where the inner gripper is an inner hole gripper. One advantage of embodying the inner gripper as an inner hole gripper in contrast to the previously utilized vacuum gripper is that an inner hole gripper can be rapidly and effectively released without the danger that, for example, air will be blown in between two substrates that are to be adhesively joined.
Pursuant to one very advantageous embodiment of the present invention, the inner and outer grippers are moveable relative to one another, and in particular the inner hole gripper is vertically moveable. Due to the relative movement, it is possible to first grasp a substrate that is to be taken up with one gripper, in order to be able to subsequently bring it into contact with the other gripper and to have it be grasped thereby.
The outer diameter of the inner hole gripper is advantageously smaller than the inner diameter of the inner hole of the substrates, in order to make it possible for the inner hole gripper to extend through a first substrate and to be able to engage a second substrate while the first substrate is engaged or held by the outer gripper. In order to effect a simple and effective manner of operation of the inner hole gripper, the inner hole gripper is preferably pneumatically actuateable.
Pursuant to one advantageous specific embodiment of the present invention, the inner and outer grippers can be actuated independently of one another in order to enable an increased flexibility of the apparatus during engagement of one or more substrates. Pursuant to one specific embodiment of the present invention, the outer gripper is a vacuum suction device having a plurality of suction devices disposed in a ring, with the suction devices ensuring a reliable grasping of the outer portions of the substrates. The ring advantageously has a convexly bent shape in order to bend or distort the rim portions of a substrate that has been taken up by the outer gripper, thereby making it possible, when a substrate that has been taken up in this manner is placed upon another substrate, for the central portion of the taken-up substrate to first come into contact with the substrate disposed below it, and only thereafter for the rim regions to come into contact, as a consequence of which again air pockets or bubbles can be prevented between the substrates. The apparatus is advantageously horizontally moveable for transport of the substrates.
The established object is furthermore realized by a method of the aforementioned type, according to which the first substrate grasped by the inner hole gripper is brought into contact with an outer gripper that grasps the substrate, the inner hole gripper is released, the inner hole gripper is moved through the hole in the first substrate, and a second substrate is grasped. With this method, two substrates can be simultaneously handled and, if desired, transported, thereby reducing the cycle times. Furthermore, the transport paths can be shortened since two substrates can be simultaneously transported, thus increasing the service life of the components utilized, especially of a drive. Furthermore, a precise centering results between the first substrate and the second substrate since the inner hole gripper respectively centers the substrates by being accommodated in their inner holes, and this centering is also maintained during the transfer to the outer gripper.
The bringing of the first substrate into contact with the outer gripper is advantageously effected by a vertical movement, and in particular by raising the inner hole gripper.
Pursuant to one preferred specific embodiment of the present invention, the grasping of the first and/or second substrate with the inner hole gripper is pneumatically controlled, since this enables a straightforward and precise control as well as a uniform grasping of the substrate at the inner hole.
The first substrate is preferably grasped by the outer gripper by means of a vacuum.
Pursuant to one preferred specific embodiment of the present invention, the rim portions of the first substrate are bent or deflected away from the second substrate, as a consequence of which during a subsequent placement of the first substrate upon the second substrate it is possible for the central portion of the first substrate to first come into contact with the second substrate, and only after a subsequent laying of the first substrate flat do the outer portions of the substrates come into contact with one another, thereby avoiding air bubbles between the substrates. The inner hole gripper and the outer gripper are preferably moved horizontally for the transport of the substrates that have been taken up.